64-Bit CPUs: Alpha, SPARC, MIPS, and POWER

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Since the very first day Alpha processors were available, they’ve held the microprocessor speed lead. Alpha consistently topped the benchmarks throughout the 1990s. The nerds’ favorite microprocessor, an engineer’s delight, and everything a good 64-bit architecture should be. It also ended up a dismal commercial failure. Is there no justice?

Digital introduced Alpha in 1992 and shipped its first Alpha processor in January 1993. Developed entirely in-house, Alpha was a replacement for the MIPS processors Digital had been using for a few years, which were, in turn, replacements for the VAX, which had become too complex for its own good.

Not entirely happy with MIPS processors, Digital’s engineers set about developing “the RISC to end all RISCs,” in the words of team member Jesse Lipcon. Code-named EVAX, for Extended VAX, each Alpha generation bore the project name EVn. Alas, EV7 was to be the last of this great dynasty.

There have really only been two major generations of Alpha processors despite the plethora of model numbers and product announcements. The 21164 and the 21264 (EV6) supplied the core for all the other processors. The 21364 (EV7) is essentially the same as the ‘264 internally but with a different external system interface. Sadly, the EV8, which was to be an entirely new internal design, was never finished. Some of the EV8 technology may be incorporated into future Intel 64-bit processors, since Compaq licensed Alpha technology to Intel last year  more on that in a bit. But note that Compaq expects to manufacture and ship Alpha chips into 2004, before converting over to IA-64.